1. Field of the Invention
This invention relates to a linear motion rolling contact bearing assembly, and, in particular, to a crossed roller linear motion rolling contact bearing assembly having a roller separator for separating the two adjacent rollers.
2. Description of the Prior Art
A linear motion rolling contact bearing assembly includes a straight rail and a slider which moves along the rail. An endless circulating path is defined in the bearing assembly, in which a plurality of rollers are provided thereby providing a rolling contact between the rail and the slider. The endless path includes a load section defined between the rail and the slider, whereby the rollers roll between the rail and the slider, a return section and a pair of connecting sections connecting the corresponding ends of the load and return sections. The rollers are typically provided in the endless path in a crossed arrangement, i.e., the adjacent two rollers being oriented with their longitudinal axes extending perpendicular to each other. Such a linear motion rolling contact bearing assembly is advantageous in that it can provide theoretically an unlimited length of relative motion between the rail and the slider.
In such a linear motion rolling contact bearing assembly, a plurality of roller separators are often provided in the endless path, each sandwiched between the two adjacent rollers, so as to reduce friction and wear of the rollers due to direct contact between the two adjacent rollers and to guide the movement of the rollers, thereby preventing the rollers from being skewed. However, with the provision of such roller separators, when the rollers move between the load or return section and the connecting section, the center-to-center distance between the two adjacent rollers varies, and, thus, a gap in the circumferential direction varies to increase the sliding resistance of the bearing assembly. As disclosed in Japanese Patent Application No. 59-38871, each of the roller separators may be provided with an elastic portion so as to absorb the fluctuations of the gap in the circumferential direction. This approach is not entirely satisfactory and there has been a need to develop a novel roller separator which can further reduce the sliding resistance of the linear motion rolling contact bearing assembly.